Overview
Challenges and Opportunities
Savannah Trial Garden
Griffin Trial Garden
Tropical Plants in Annual Beds
Landscape Considerations for Tropical Plants
Production Consideration
Selling Foliage for Landscape
Marketing Strategies
Summary and Table

Tropical Plants Offer
New Possibilities
for Georgia Gardens

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Bodie Pennisi and Paul Thomas, Extension Horticulture Specialists
Allan Armitage, Professor of Horticulture






Overview

Consumers and avid home gardeners have become more adventurous with their plant choices, and are prompting other growers and landscapers to become more savvy in catering to this spirit of landscape adventure. Anything that adds interest to the landscape design and makes it unique can evolve into a trend - incorporating more non-traditional plants, for example, such as exotic and tropical annuals and perennials. But Flowers are taking a step back, leaving the landscapers to focus on the foliage instead, and to explore variations in texture and color.


Figure 1. Tropical plants in the landscape can create an exotic garden, an impression of an island paradise. or a tamed jungle with all of its magic and mystery.

Text Box: Tropical Plants

Challenges and Opportunities for the Ornamental Industry in Georgia

The seemingly insatiable consumer demand for new plants presents a challenge and an opportunity for the Georgia ornamental industry. Georgia has a diverse climate (Fig. 2), from zone 8b in the South and coastal areas, where minimum average temperatures range from 15-20 degrees Fahrenheit, to zone 7a in the northern mountain region, where minimum average temperatures range from 0-5 degrees Fahrenheit. A small part of North Georgia is in Zone 6b where minimum average temperatures range from -5 to 0 degrees Fahrenheit.   The largest area in the state is divided almost equally between zones 8a (minimum average temperatures range from 10-15 degrees F) and 7b (minimum average temperatures range from 5-10 degrees F).

Each of these areas is characterized by unique climate, which presents both a challenge and an opportunity for industry and consumers. On one hand, recommending plants that would do well in all areas is difficult; on another, plants that grow well in one area but not in another provide an excellent opportunity for local use. This is especially true for tender plants that may thrive in the warm weather and may even come back the next season in one area, but not in other areas. Such plants may receive enormous recognition seven to eight months of the year, but because they are not truly

Text Box: Georgia Climate Zones

Figure 2. Georgia climate zones with average minimum temperature ranges and examples of cities in those areas 9adapted from USDA hardiness map (www.usda.gov).

perennial (able to survive the cold weather and grow back the next season), they may not get recommended and/or marketed by the industry. Some of these plants, termed tender perennials, tropicals, etc. , may receive much attention in northern areas in Florida, for example, while few growers and garden centers in South Georgia market them - although both are in the same climate zone. Thus the consumer in Georgia may be largely unaware of the benefits of these tender perennials.

In addition, many plants from the tropics hold up very well in Georgia's challenging spring and summer months, and can tolerate extremes of heat, humidity, and moisture. Some are so uniquely adapted to low-light environments that they can be used in deep-shade areas in a garden. Shade gardening, however, has challenged landscapers because of a limited selection of species, which do well in low light environments. Few flowering plants perform well in such areas, especially where light levels dip below 1000 ft-c; for example, under oak shade, light levels frequently average around 500 ft-c. Tropical plants adapted to deep shade are uniquely suited to thrive in low-light habitats with high humidity. Many of them, because of their epiphytic origins, are capable of using small amounts of dew moisture, which accumulates in the early morning hours during summer, either by direct absorption through the foliage or by channeling moisture into their leaf whorl.

Tropical plants may also be used in annual beds in combination with traditional flowering plants.

The bold vegetative look of foliage plants can add height and texture, while achieving a tropical look that is attractive and highly sought after.

Yet the use of tropical plants may not be limited to landscape. Combination gardens in various-sized containers have become very popular with consumers. Visually appealing and colorful combinations using tropical plants alone or in combination with other flowering plants can be created (Fig. 3). Such gardens hold high appeal for gardeners in urban areas because of the limited garden space.

Text Box: Comination Garden (High- and Low-Light Adapted Plants

Figure 3. Colorful combination gardens created exclusively with tropical foliage plants. The combination container on the left features high-light adapted plants and can be used on patios, sundecks, around pools, etc. The container on the right uses plants best adapted for low-light environments. During the cold months, a combination garden can be brought inside the house and treated as an indoor planting. This further illustrates the versatility of tropical plants.

Finally, numerous new tropical species and cultivars - many with bold, multicolored foliage, and quite a few flowering varieties - have come to market in recent years. Some new introductions show improved cold tolerance and have been used successfully in landscapes throughout southern states, especially in Florida.

Further exploration of the landscape potential of new ornamental species and cultivars is needed and could provide recommendations and guidelines to the industry and consumers. The goals of these investigations were to achieve an aesthetically pleasing landscape while experimenting with mixing various plant habits, leaf textures and colors, and even flowers, and to raise consumer awareness, both at industry and public levels, of the alternative uses of tropical plants in the landscape.

This publication presents plant performance data collected over a three-year period in trials from two different Georgia environments, a coastal area and a mid-state area.

Trial Gardens Locations, Conditions, and Plant Performance

Tropical Plant Trial Garden at the Bamboo Farm and Coastal Gardens in Savannah, Georgia (evaluation period April 2002 - October 2004)

Text Box: Full Shade Bed at Bamboo Farm

Figure 4. Full shade bed at the Bamboo Farm and Coastal Gardens in Savannah, GA.

Plant Performance and Hardiness

Table 1. Percent survival and growth in second and third years for species and cultivars in the Savannah Trial garden during the evaluation period April 2000 - October 2004.ß

Species and cultivar

% survival

Growth in second and third year

(% of first year)

Alocasia gagaena

92

90

Alocasia odora

83

90

Alocasia wentii

58

35

Alocasia macrorrhiza

75

70

Colocasia nancyana

75

75

Colocasia 'Black Magic'

67

65

Colocasia illustris

58

60

Musa zebrina

92

90

Siphonochilus decora

92

90

Globba 'White Dragon '

100

90

Alpinia zerumbet

58

65

Cornukaempferia
'Jungle Gold'

83

95

Kaempferia 'Alva'

83

85

Kaempferia 'Grande'

92

95

Calathea tigrinum

75

65

Calathea 'Ice Blue'

83

85

Ficus benjamina 'Midnight'

85

35

Spathiphyllum 'Petite'

90

95

Schefflera 'Luseanne'

50

30

 
Text Box: C. Globba (White Dragon) Text Box: D. Siphonocilius Decora
Midnight Text Box: F. Spathiphyllum (Petite)
Text Box: G. Calathea (Ice Blue)

Figure 5. Regeneration and growth of plants in the Savannah Trial garden. A. Alocasias and Colocasias. B. Calathea tigrinum. C. Globba 'White Dragon'. D. Siphonocilius decora . E. Ficus benjamina 'Midnight'. F. Spathiphyllum 'Petite'. G. Calathea 'Ice Blue'.


Tropical Plant Trial Garden at the Research and Education Gardens, Griffin, Georgia (evaluation period May-December 2004)

 
Text Box: D. Full Shade

Figure 6. Trial areas at the Research and Education Gardens, Griffin, GA. A. Full sun. B. Part sun (morning shade, midday sun, afternoon shade). C. Part shade (no direct sun). D. Full shade.


Plant Performance and Hardiness

Tropical Plants in Annual Beds

Tropical foliage plants may be used in annual beds in combination with traditional flowering plants. The bold vegetative look of foliage plants can add height and texture, while achieving a tropical look that is attractive and highly sought. Many of these plants tolerate high light conditions and are therefore suitable for use in combination with traditional summer bedding plants such as salvia, marigold, begonia, zinnia, etc. For light requirements of individual species, refer to Table 4. Foliage texture varies from fine (asparagus and Boston ferns) to coarse (crotons) (Table 4). A wide variety of foliage colors, including bright yellow, orange and red, are typical of older croton varieties. The newer crotons offer a variety of leaf shapes as well.

Landscape Considerations for Tropical Plants

If you are considering using foliage plants, you should trial them outdoors, on a limited basis under the specific conditions (temperature, light intensity, humidity, air movement, soil type and topography) they will encounter in your particular landscape setting. For best results, the soil should be well-drained, rich in organic matter, with a pH range of 5 to 6.5. The soil should not be allowed to become exceedingly dry.

High visual impact combinations using plants evaluated in our trials are illustrated in Figure10.

Production Considerations

Growers in Georgia have several options for obtaining starter material, including rooted liners in cell packs and small pots, rooted air layers and rooted cuttings. Plants can also be purchased as finished products (cell packs to small size pots) and resold without spending any production time in the greenhouse. A few of the taller species can be grown or purchased in larger containers (6-inch and larger). Production times vary depending on species, container size, growing season and geographic location.

Root-zone heating (70 degrees F) can be used to speed up production. Most of the plants listed in Tables 2 and 3 can be produced under light levels of 5,000 to 7,000 footcandles. These growing conditions would produce vigorous, compact liners or potted plants well adapted to northern summer conditions, ranging from 75 percent shade to full sun. If plants are started in northern greenhouses, they may require an acclimatization period under a partially shaded area outside with higher light levels before exposing them to full sun landscapes.

The plants should be trialed outdoors, on a limited basis under the specific conditions (temperature, light intensity, humidity, air movement, soil type and topography) they will encounter in a landscape setting. For best landscape results with plants listed in Tables 2 and 3, the soil should be well-drained, rich in organic matter, with a pH range of 5 to 6.5. The soil should not be allowed to become exceedingly dry.

Selling Foliage for Landscapes

Foliage plants offer landscapers new design elements and can help create a niche for growers. Growers should compare production costs versus shipping costs of finished plants. Foliage plants for landscape should be marketed right along with bedding plants. However, the foliage should be priced appropriately because of plants' higher production and/or shipping costs. The foliage could be marketed as specialty annuals.

A number of plants discussed are used in central and southern Florida landscapes and as interiorscape plants in the north. It is very likely that some landscapers and consumers may identify these plants as for "interior use only" and may be reluctant to plant them outdoors.

Here are some points to you can discuss with potential customers who may be reluctant to use foliage plants outdoors.